The U.S. Department of Homeland Security and the Transportation Security Administration and other similar agencies throughout the world have the daunting task of identifying dangerous devices and/or contraband within passenger baggage and within a time-frame that will not generally impede passenger travel time. Many X-ray baggage scanning systems in use today are of the “line scanner” type and include a stationary X-ray source, a stationary linear detector array, and a conveyor belt for transporting baggage between the source and detector array as the baggage passes through the scanner. The X-ray source generates a stationary X-ray beam that passes through and is partially attenuated by the baggage, as the baggage is moved into and positioned within the beam, before being received by the detector array. During each measuring interval, each detector of the detector array generates data representative of the integral of the density of the planar segment of the baggage through which the detected portion of the X-ray beam passes. The data acquired by the detector array during each measuring interval is used to form one or more raster lines of a two dimensional image. As the conveyor belt transports the baggage past the stationary source and detector array, the scanner generates a two dimensional image representative of the density of the baggage, as viewed by the stationary detector array. The density image is typically displayed for analysis by a human operator.
It has been suggested to use X-ray computed tomography (CT) as a part of a baggage scanner to identify objects within baggage positioned in the scanner. At least one of these designs, described in U.S. Pat. No. 5,182,764 (Peschmann et al.) and U.S. Pat. No. 5,367,552 (Peschmann et al.) (hereinafter the '764 and '552 patents), for example, has been commercially developed and are referred hereinafter as the “In Vision Machine”. The In Vision Machine includes a CT scanner of the third generation type. Third generation type CT scanners are particularly useful in the medical arts and are often used for imaging sections of the human body. Third generation scanners typically include an X-ray source and an X-ray detector system secured respectively to diametrically opposite sides of an annular-shaped gantry platform or disk. The gantry disk is rotatably mounted within a gantry support so that in operation the disk continuously rotates about a rotation axis while X-rays pass from the source through an object positioned within the opening of the disk to the detector system. During a scanning procedure, baggage passes along the rotation axis through the rotating gantry disk.
The EXACT™ AN6000, which is available from International Security Systems Corporation, which is a subsidiary of the assignee of the present disclosure, Analogic Corporation, is an advanced CT system for the detection of explosives, drugs, and other contraband in carry-on baggage. The EXACT™ AN6000 generates 3-D image data of all objects in a bag, gathers all data in one pass, allows automatic analysis of entire contents of bag, and can handle up to 600 bags per hour. Analogic's EXACT™ AN6000 is a dual energy, helical-cone-beam, multi-slice CT system that provides a complete set of CT images of an entire three-dimensional object as it passes along the baggage conveyor. The system includes a high efficiency, wide dynamic range, solid-state X-ray detector array consisting of 6048 detectors. Rotating at 90 RPM, this system takes up to 720 sets of 6048 measurements per rotation every two-thirds of a second. The system presents both projection and axial images of this moving object for analysis by the operator. The EXACT™ AN6000 CT system is covered by at least the following U.S. patents which are owned by Analogic Corporation: U.S. Pat. Nos. 5,661,774; 5,796,802; 5,818,897; 6,185,272; 6,188,745; and 6,418,189.
The EXACT™ AN6000 is the heart of the eXaminer 3DX™ 6000 Explosive Detection System (EDS), the first single-unit, second-generation CT system certified by the U.S. Federal Aviation Administration and developed in cooperation with L-3 Communications. The EXACT™ AN6000 is also the system of choice for detection of drugs and other contraband. Equipped by ISS with our own workstation and custom drug algorithms, the EXACT™ AN6000 has been successfully demonstrated to the U.S. Customs Service, detecting small quantities of contraband. Sophisticated software automatically isolates bag contents unambiguously and analyzes them, evaluating them against the known characteristics of explosives or narcotics. If a match is found, the system alerts the operator, highlights the area of concern for further analysis, and provides a full rotating 3-D image of the potential threat.
What is still desired is a system for detecting explosives, drugs, and other contraband in objects larger than a typical piece of carry-on luggage, such as an air cargo container containing a plurality of pieces of luggage. Preferably, the system will be an X-ray computed tomography scanning system adapted to scan air cargo containers or other larger containers for detection of explosives, drugs, and other contraband.